Thermal decomposition of liquid 1,1-Dinitropropane (DNP) at 1 and 1000 atm and 135-155 C gives over 90% propionic acid. The reaction is accelerated by pressure and by added water. 2,2-DNP decomposed slowly at 165 C to give only acetone, NO and NO2. Reactions of isobutane and neopentane with NO2-N2O4 indicated that HNO3 is an intermediate oxidizer in these reactions. The gas-phase decompositions of four dinitropropanes have been studied, using low-pressure pyrolysis. Detonation failure diameters of nitromethane, 1,1- dinitroethane, 1,1-dinitropropane, and 2,2-dinitropropane were measured for the cases of heavy confinement in thick-walled lead cylinders and Dremin's weak shell confinement. Shock-induced reaction times and failure wave velocities in decaying detonation wave were also measured and used in the Dremin-Trofimov model to calculate failure diameters of the unconfined liquids.